The use of instruments in ocular surgical applications is well known. One widely used type of instrument is an ultrasonic hand piece that is used in ophthalmic applications, such as in the removal of cataracts from the eye by phacoemulsification.
FIG. 1 depicts one such type of prior art ultrasonic hand piece as shown in U.S. Pat. No. 4,504,264 of Kelman. This hand piece has a housing 10 of, for example, plastic or metal, within which is supported a transducer means 11 for generating mechanical vibrations upon excitation with an alternating-current electrical signal. The transducer 11 is shown as a magnetostrictive transducer with an electrical coil 12 wound about a stack of metal laminations so that longitudinal mechanical vibrations are produced. The transducer can also be of the piezoelectric type. There is a connecting body 16 of, for example, titanium, having a reduced diameter distal end portion, which also can be an attached separate portion. The connecting body forms an acoustic impedance transformer for conveying the longitudinal vibrations of the transducer 11 for application to an operative tool or working tip 14 connected to the distal end of the connecting body 16.
The work tip 14 is connected, such as by a screw thread, to the narrowed distal end of the connecting body 16 so as to be coupled to the transducer 11. As a result, the work tip is longitudinally vibrated by the transducer. The working tip 14 is an elongated, hollow tube of a suitable metal, such as titanium, that is capable of supporting ultrasonic vibrations. It has a distal end of a desired shape to be placed against the tissue to be removed. The work tip 14 has a base portion 15 in threaded engagement with the distal end of the connecting body 16. The tip 14 can be interchanged by use of the screw threads.
The distal end of the tube 14 is shown surrounded by a sleeve 17, which may be made of a material such as silicone, whose proximal end 18 is supported in threaded engagement on a reduced diameter end of the housing 10. If desired, the proximal end of sleeve 17 can be engaged more proximally along the length of the housing 10. The connecting body 16 has two elastomeric 0-rings 19, 20 on its outer surface. These provide a fluid-tight seal between the connecting body 16 and the transducer means 11. A plurality of screws 51 are shown disposed around the axis of the housing 10 for preventing longitudinal displacement (other than vibration) or rotational movement of the vibratory structure within the housing and also for radial centering of the vibratory structure within the housing. Other types of conventional mounting arrangements can be used.
The hand piece also illustratively has electrical input terminals 40, 41 for applying a suitable electrical signal to the magnetostrictive transducer 11. Cooling water is shown provided inside the housing 10 from an inlet 42 to an outlet 43 and within a chamber between 0-ring 19 and a grommet 50 for circulation around the transducer. This is not always necessary and is not used in most present day hand pieces.
The sleeve 17 around the end of tube 14 forms a first fluid passage 21 between the tip 14 and the sleeve for an infusion/irrigation fluid. An inlet 22 is provided on the housing or sleeve distally of the 0-ring 20 for supplying the irrigation fluid to the passage 21 from a fluid supply, e.g., a bag of saline solution (not shown).
A passage 23 is formed through the connecting body 16 that is in communication with a central passage 25 of the work tube 14. An outlet 24 on the housing or sleeve receives a suction (aspiration) force that is applied to the passage 23 in the connecting body and the central passage 25 in the work tip tube 14. A chamber 31 is formed between the spaced 0-rings 19, 20 on the body 16 and the housing 10, with which the aspiration force from outlet 24 communicates. Thus the aspiration force is from the source (e.g., a suction pump not shown), into the chamber 31 between the 0-rings, through the passage 23 in the connecting body and the passage 25 in the work tip 14. Tissue that is emulsified by impact with the work tip tube 14 is aspirated from the operating site by the aspiration flow force through the tube. In particular, saline solution introduced into the eye through fluid passage 21 and tissue displaced by the vibration force of the tube 14, is drawn into the distal end of passage 25 and passes out of the hand piece through outlet 24. It should be noted that passage 25 is located concentrically within passage 21.
Considering now the operation of the hand piece of FIG. 1. When an electrical signal having a frequency of, for example, 40,000 cycles/second is applied to the coil 12 around the magnetostrictive transducer 11, the transducer 11 vibrates longitudinally at 40,000 cycles per second, thereby vibrating the connecting bodies 13, 16 and the work tip tube 14. Treatment fluid is supplied through inlet 22 and fluid passage 21 to bathe the tissue in the operating site region around the working tip tube 14. Suction force is applied through inlet 24 and passage 23 to the working tip tube 14 passage 25 to withdraw the tissue fragmented by the work tip along with some of the treatment fluid.
Instruments of the type described above are often used in cataract surgery in which the eye lens is removed from the eye capsule and an intra-ocular lens (IOL) is then implanted. In such a procedure before the IOL is implanted it has been found to be desirable to cleanup lens substance and lens epithelial cells (LEC's) in the capsular bag of the eye and to remove them. Doing this procedure provides a more stable and long-term fixation for certain types of IOL's in the capsular bag. One manner of accomplishing the cleanup is to use a combination of low force irrigation of the capsular bag interior with a liquid together with the application of low power ultrasonic energy. This dislodges the unwanted cells and substances without damage to the capsular bag. Further, this material can be removed from the capsular bag by the aspiration fluid flow, which also may be reduced in pressure to avoid damage.
In a cleanup procedure it is advantageous if the flow of the irrigation liquid can be made more directional than would be possible using the hand piece with the outer sleeve through which the liquid flows and exits from around the work tip that produces the ultrasonic energy. It is also better if the aspiration force is lower. As a result, typically a different tip from the one illustrated in FIG. 1, which breaks up the tissue, is used for the cleanup. In fact a completely different instrument called an irrigation or infusion/aspiration (I/A) instrument is often used for this purpose. Such an instrument typically has concentric infusion and aspiration lumens, and typically has no ultrasonic vibration capability. The infusion fluid is in an outer concentric lumen so that its flow surrounds the distal part of lumen of the work tip. The aspirated tissue enters a small hole in the distal part and is withdrawn through the central lumen. Thus, when the phacoemulsification has been completed and cleanup is to be started, the surgeon must remove the phacoemulsification tool from the eye. Then the surgeon removes the first or phacoemulsification work tip, replaces it with a different cleanup work tip and then inserts the new work tip or a separate I/A tool is inserted in to the eye. This second insertion into the eye increases the possibilities of infection and trauma. Also, the I/A tool has a disadvantage in that the surgeon would have to keep inserting and withdrawing the ultrasonic work tip and the I/A tool from the eye as the process is completed, because the surgeon cannot be sure that all of the tissue has be broken up until the cleanup process has begun. As a result, this would also subject the patient to the increased possibilities of infection and trauma.
As shown in the present inventor's own U.S. Pat. No. 8,641,658, the surgical instrument may be provided with dual lumens in tubes 132, 134, each of which can alternatively be used for aspiration of emulsified tissue and irrigation of the surgical site. FIG. 2 shows a work tip 130 that can be connected to an ultrasonic energy source 102 of a hand piece by means of a connecting body 204. Two fluid passages 120 and 180 for aspiration or irrigation fluid pass through the connecting body 204. For example the proximal end of passage 120 can be in communication with the irrigation fluid input of the supply line 124 and the proximal end of passage 180 can be in communication with the aspiration fluid of the supply line 164. The distal ends of the two passages 120 and 180 terminate at the distal end of the connecting body 204.
There are threads 182 around the connecting body distal end. A hub 190 is around the proximal ends of the work tip tubes 132 and 134, which are bent so that the proximal ends of their lumens are parallel to the distal ends of the connecting body passages 120 and 180. A collar 194 with internal threads on its open end has its flange end rotatably mounted in a groove 192 in the hub 190. There are mating index pieces, such as mating grooves and ribs or pins (not shown), on the opposing faces of the connecting body 204 distal end and the hub 190 so that the proximal end of the lumen of tube 132 will be aligned with the distal end of connecting body passage 120 and the proximal end of the lumen of tube 134 aligned with the distal end of passage 180.
When the tubes and connecting body are properly aligned the collar 194 is tightened on the connecting body threads 182 and the lumens at the proximal ends of tubes 132 and 134 will be brought into fluid communication with the distal ends of the connecting body passages 120 and 180. O-rings 193 are provided in the connecting body at the distal ends of passages 120 and 180 to make the communications fluid tight.
Both of the tubes 132 and 134 receive the ultrasonic energy from the source 102 (not shown). A valve (not shown) can be used with the hand piece of FIG. 2 to switch the fluid flow from the sources 124 and 164 to the lumens of tubes 132 and 134 of the integrated work tip. Since both tubes 132 and 134 receive ultrasonic energy the emulsification of tissue and its aspiration can take place through either one in addition to each tube being able to supply irrigation liquid through the different types and shapes of openings at the distal ends of the tubes.
The work tip can be used with only an irrigation/aspiration (I/A) function by turning off the source of ultrasonic energy and only supplying the aspiration and irrigation fluids. Thus, the same instrument can be used for the phacoemulsification function while performing irrigation and aspiration as an operation takes place and also only for I/A functions (no or minimal ultrasonic energy is used) useful for cleaning the capsular bag as described above. This eliminates the need for the surgeon changing instruments and also provides the surgeon with a work tip having two tubes with different shape openings available for both aspiration and irrigation.
Only one of the tubes, e.g., 134, can be used as an I/A work tip. In the oval shaped openings 165 along the tube length can be used alone in the eye capsular bag for the substance and cell cleanup procedure described above. The oval shaped openings 165 allow for both good dispersion of the irrigation fluid or a large area for aspiration of cells and substances dislodged by the irrigation liquid.
Since the beginning of phacoemulsification surgery, cataracts have been removed by ultrasonic vibration of a hollow titanium needle or needles. There has never been any other proposal of a way to remove a cataract by ultrasonic vibration, other than by means of a hollow needle. The reason for this is that the end of the needle or tube contacts the tissue directly. Therefore the pieces of tissue are directly in front of the tube end as they are separated and can be easily drawn into the open end of the tube by the aspiration force. However, in order to provide the ultrasonic energy to the tissue, the thin needle must be made of a very strong material. Also the material should be biocompatible. Titanium has been the material of choice.
Titanium, however, is a material that is hard to work with and is expensive. In the early days of phacoemulsification the cost for surgery was high and the expense of the titanium needle was of no great concern. However, as the surgical cost has come down and since there has been increased pressure to reduce medical costs; the cost of the needle has become significant. The expense of titanium and the difficulty of working with it are even more significant with the present inventor's dual lumen work tip as illustrated in U.S. Pat. No. 8,641,658. With this design, not only are there two titanium tubes, but their proximal ends have significant bends that prove to be a manufacturing challenge when titanium is used.
In prior times after a phacoemulsification procedure, the instruments (including the work tip tube) were sterilized for use with another patient. However, as disclosed for example, in the present inventor's U.S. Patent Application Publication No. 2015/0025451 A1 (FIG. 5), the work tip and its supporting hub can now be discarded after each use along with a sterile sheet or bag. This saves the expense of sterilization and speeds up the operation so that more patients can receive the surgery in a single day, thus reducing the cost to each. The problem is that this disposable work tip creates even more impetus to reduce its cost.